Homomultivalent and heteromultivalent inhibitors of prostate specific membrane antigen (pmsa) and uses thereof

ABSTRACT

The present invention provides bivalent and multivalent ligands with a view to improving the affinity and pharmacokinetic properties of a urea class of PSMA inhibitors. The compounds and their synthesis can be generalized to multivalent compounds of other target antigens. Because they present multiple copies of the pharmacophore, multivalent ligands can bind to receptors with high avidity and affinity, thereby serving as powerful inhibitors. The modular multivalent scaffolds of the present invention, in one or more embodiments, contains a lysine-based (α-, ε-)dialkyne residue for incorporating two or more antigen binding moieties, such as PSMA binding Lys-Glu urea moieties, exploiting click chemistry and one or more additional lysine residues for subsequent modification with an imaging and/or therapeutic nuclides or a cytotoxic ligands for tumor cell killing.

REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 61/565,179, filed on Nov. 30, 2011, which is herebyincorporated by reference for all purposes as if fully set forth herein.

STATEMENT OF GOVERNMENTAL INTEREST

This invention was made with U.S. government support under grant nos.5RO1CA134675-03 and 1K25CA148901-01A1. The U.S. government has certainrights in the invention.

BACKGROUND OF THE INVENTION

Prostate cancer (PCa) will kill an estimated 33,720 men in the US alonethis year. The integral membrane protein prostate-specific membraneantigen (PSMA) is becoming increasingly recognized as a viable targetfor imaging and therapy of prostate and other forms of cancer. PSMA issignificantly over-expressed in PCa and metastases, particularly withrespect to the castration-resistant form. Accordingly, PSMA may providea negative prognostic indicator for PCa—enabling distinction of indolentfrom aggressive disease. Imaging PSMA has also provided insight intoandrogen signaling and information on response to taxane therapy.

Recently the present inventors and others have demonstrated successfulPSMA-targeted radionuclide imaging in experimental models of PCa usingcysteine-glutamate or lysine-glutamate ureas. With those agents theradionuclide (¹¹C, ¹²⁵I, ¹⁸F) is attached to the cysteine or lysinemoiety via a small prosthetic group. For large molecular fragments, suchas radiometal (^(99m)Tc, ⁶⁸Ga, ¹¹¹In) chelators, organic fluorescentmolecules, and nanoparticles, we have determined that a linking moietyof at least 20 Å (long-linker) between the large molecule and the lysinemoiety facilitates productive binding. We have also developed aPSMA-targeted, dual (radionuclide and optical) modality imaging platformthat enables sequential, dual modality imaging.

Various approaches have been reported to exploit multivalent scaffoldsfor the construction of molecular imaging probes. However, the chemistryused to produce them can become complicated, even more so when abifunctional chelator must be attached to a separately multimerizedconstruct to introduce a radionuclide, for example, for imaging.Although, the concept of multimerization for PSMA targeted,near-infrared imaging agents has been proffered for in vitro cellbinding studies, to our knowledge a multivalent PSMA-binding agent hasnot yet been shown to image PSMA successfully in vivo.

Therefore, there still exists a need to provide better and moreconvenient methods for creating scaffolds for multimeric presentation ofPSMA and other targeting species including bivalent and multivalentforms, over the corresponding monomer, to target antigens in vivo.

SUMMARY OF THE INVENTION

In accordance with one or more embodiments, the present inventionprovides bivalent and multivalent ligands with a view to improving theaffinity and pharmacokinetic properties of a urea class of PSMAinhibitors. The strategy we employ can be generalized to multivalentcompounds of other target antigens. Because they present multiple copiesof the pharmacophore, multivalent ligands can bind to receptors withhigh avidity and affinity, thereby serving as powerful inhibitors.

The modular multivalent scaffolds of the present invention, in one ormore embodiments, contains a lysine-based (α-, ε-)dialkyne residue forincorporating PSMA binding Lys-Glu urea moieties exploiting clickchemistry and one or more additional lysine residues for subsequentmodification with an imaging and/or therapeutic nuclides or a cytotoxicligands for tumor cell killing.

In an embodiment, the divalent agent has a prolonged biologicalhalf-life and enhanced specific binding and retention in tissuesexpressing PSMA.

In accordance with an embodiment, the present invention provides acompound of formula I:

wherein Z is H, CO₂H, NH₂, SH and OH;wherein m is 2 to 16;wherein R₁ is the same or different moiety and is a compound of formulaVII:

wherein W is C₁ to C₁₀ alkyl, alkylamino, alkyl, alkylamino, alkenyl,alkynyl, hydroxyalkyl, alkoxy, dialkylamino thioalkyl, thioalkenyl,thioalkynyl, aryloxy, acyloxy, thioacyl, amido, and sulphonamido;wherein each of alkyl, or aryl moiety may be unsubstituted orsubstituted with one or more substituents selected from the groupconsisting of halo, hydroxy, carboxy, phosphoryl, phosphonyl, phosphonoC₁-C₆ alkyl, carboxy C₁-C₆ alkyl, dicarboxy C₁-C₆ alkyl, dicarboxy haloC₁-C₆ alkyl, sulfonyl, cyano, nitro, alkoxy, alkylthio, acyl, acyloxy,thioacyl, acylthio, aryloxy, amino, alkylamino, dialkylamino,trialkylamino, arylalkylamino, guanidino, aldehydo, ureido, andaminocarbonyl; W may be substituted with a chelating moiety, afluorescent dye or H, wherein when W is a chelating moiety, it can bebound to a metal ion useful in imaging, or as a cytotoxic moiety; and Lis a linker, wherein the linker is a C₈ to C₂₀ alkyl, alkylamino,alkenyl, alkynyl, hydroxyalkyl, alkoxy, dialkylamino thioalkyl,thioalkenyl, thioalkynyl, aryloxy, acyloxy, thioacyl, amido,polyethylene glycol and sulphonamido, wherein each of alkyl or arylmoiety may be unsubstituted or substituted with one or more substituentsselected from the group consisting of halo, hydroxy, carboxy,phosphoryl, phosphonyl, phosphono C₁-C₆ alkyl, carboxy C₁-C₆ alkyl,dicarboxy C₁-C₆ alkyl, dicarboxy halo C₁-C₆ alkyl, sulfonyl, cyano,nitro, alkoxy, alkylthio, acyl, acyloxy, thioacyl, acylthio, aryloxy,amino, alkylamino, dialkylamino, trialkylamino, arylalkylamino,guanidino, aldehydo, ureido, and aminocarbonyl; and alternatively, R₁ isa peptide ligand to an enzyme or endothelial receptor, and wherein R₂ isa chelating moiety, a fluorescent dye or H, wherein when R₂ is achelating moiety, it can be bound to a metal ion useful in imaging, oras a cytotoxic moiety; or a pharmaceutically acceptable salt, solvate,or stereoisomer thereof.

In accordance with another embodiment, the present invention provides acompound of formula II:

wherein Z is H, CO₂H, NH₂, SH and OH;wherein R₁ is the same or different moiety and is selected from thegroup consisting of:

and alternatively, R₁ is a peptide ligand to an enzyme or endothelialreceptor; and wherein R₂ is a chelating moiety, a fluorescent dye or H,wherein when R₂ is a chelating moiety, it can be bound to a metal ionuseful in imaging, or as a cytotoxic moiety; or a pharmaceuticallyacceptable salt, solvate, or stereoisomer thereof.

In accordance with a further embodiment, the present invention providesa compound of formula VI:

wherein R₁ is the same or different moiety and is a compound of formulaVI:

wherein W is C₁ to C₁₀ alkyl, alkylamino, alkyl, alkylamino, alkenyl,alkynyl, hydroxyalkyl, alkoxy, dialkylamino thioalkyl, thioalkenyl,thioalkynyl, aryloxy, acyloxy, thioacyl, amido, and sulphonamido;wherein each of alkyl, or aryl moiety may be unsubstituted orsubstituted with one or more substituents selected from the groupconsisting of halo, hydroxy, carboxy, phosphoryl, phosphonyl, phosphonoC₁-C₆ alkyl, carboxy C₁-C₆ alkyl, dicarboxy C₁-C₆ alkyl, dicarboxy haloC₁-C₆ alkyl, sulfonyl, cyano, nitro, alkoxy, alkylthio, acyl, acyloxy,thioacyl, acylthio, aryloxy, amino, alkylamino, dialkylamino,trialkylamino, arylalkylamino, guanidino, aldehydo, ureido, andaminocarbonyl; W may be substituted with a chelating moiety, afluorescent dye or H, wherein when W is a chelating moiety, it can bebound to a metal ion useful in imaging, or as a cytotoxic moiety; and Lis a linker, wherein the linker is a C₈ to C₂₀ alkyl, alkylamino,alkenyl, alkynyl, hydroxyalkyl, alkoxy, dialkylamino thioalkyl,thioalkenyl, thioalkynyl, aryloxy, acyloxy, thioacyl, amido,polyethylene glycol and sulphonamido, wherein each of alkyl or arylmoiety may be unsubstituted or substituted with one or more substituentsselected from the group consisting of halo, hydroxy, carboxy,phosphoryl, phosphonyl, phosphono C₁-C₆ alkyl, carboxy C₁-C₆ alkyl,dicarboxy C₁-C₆ alkyl, dicarboxy halo C₁-C₆ alkyl, sulfonyl, cyano,nitro, alkoxy, alkylthio, acyl, acyloxy, thioacyl, acylthio, aryloxy,amino, alkylamino, dialkylamino, trialkylamino, arylalkylamino,guanidino, aldehydo, ureido, and aminocarbonyl; and alternatively, R₁ isa peptide ligand to an enzyme or endothelial receptor, and wherein R isa chelating moiety, a fluorescent dye or H, wherein when R is achelating moiety, it can be bound to a metal ion useful in imaging, oras a cytotoxic moiety; or a pharmaceutically acceptable salt, solvate,or stereoisomer thereof.

In accordance with still a further embodiment, the present inventionprovides a compound of formula V:

wherein R₁ is the same or different moiety and is selected from thegroup consisting of:

and alternatively, R₁ is a peptide ligand to an enzyme or endothelialreceptor; and wherein R is a chelating moiety, a fluorescent dye or H,wherein when R is a chelating moiety, it can be bound to a metal ionuseful in imaging, or as a cytotoxic moiety; or a pharmaceuticallyacceptable salt, solvate, or stereoisomer thereof.

In accordance with an embodiment, the present invention provides apharmaceutical composition comprising a compound, salt, solvate, orstereoisomer of any one of the compounds described above, and apharmaceutically acceptable carrier.

In accordance with an embodiment, the present invention provides apharmaceutical composition comprising a compound, salt, solvate, orstereoisomer of any one of the compounds described above, and at leastone or more other biologically active agents.

In accordance with an embodiment, the present invention provides amethod of treating or preventing cancer in a subject comprisingadministering to the subject an effective amount of a compound, salt,solvate, or stereoisomer of any one of the compounds described above, orthe pharmaceutical compositions described above.

In accordance with an embodiment, the present invention provides amethod of imaging prostate cancer in a subject comprising administeringto the subject an effective amount of a compound, salt, solvate, orstereoisomer of any one of the compounds described above, or thepharmaceutical compositions described above wherein R or R₂ is an metalion or dye useful for imaging.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts certain embodiments of the present invention.

FIG. 2 shows a schematic depiction of the synthesis of compound 3 of thepresent invention. (a) 20% piperidine in DMF; (b) Fmoc-Lys(Fmoc)-OH,PyBOP, DIEA, DMF; (c) 20% piperidine in DMF; (d) propiolic acid, EEDQ,DMF, microwave irradiation; (e) TFA, H₂O, TES; (f) compound 1, Cu(OAc)₂,Na-Ascorbate, t-BuOH-water; (g) DOTA-NHS, DIEA, DMF

FIG. 3 depicts IC₅₀ curves for compounds 1-3 of the present invention.

FIG. 4 shows SPECT-CT imaging of [¹¹¹In]3 of the present invention usingPSMA+PIP and PSMA− flu tumors in a male SCID mouse. The mouse wasinjected intravenously using a single dose of 44.4 MBq (1.2 mCi) of[¹¹¹In]3. Radiochemical uptake was followed up to 192 h post-injection(decay corrected).

FIG. 5 is the structure of a monovalent compound, [¹¹¹In]5.

DETAILED DESCRIPTION OF THE INVENTION

The compositions and methods of the present invention described hereinare able to be generalized to other modalities and for molecularradiotherapy. Since DOTA is a general chelating agent, compound 3 of thepresent invention may also be used with other radiometals such as ⁶⁸Ga,⁶⁴Cu or ⁸⁶Y for positron emission tomography (PET) or ⁹⁰Y and ¹⁷⁷Lu fortherapy. Technetium-99m can also be incorporated by replacing DOTA withstandard peptide-based chelating agents containing nitrogen and sulfurdonors (N₃S, N₂S₂), the HYNIC chelator or by use of single amino acidchelating (SAAC) agents. Further attesting to its utility, the compoundsof the present invention, such as bivalent compound 2 can also be usedas a versatile intermediate for medically important nonmetals, such asthe radiohalogenated imaging isotopes ¹⁸F, ¹²³I or ²¹¹At/¹³¹I forradiotherapy. Other fluorophores/chelatingagents/radiometals/nonmetals/cytotoxic agent combinations can also beenvisioned using this approach. Another significant aspect of themultivalent scaffold is that it enables the generation systematically ofat least 4- and 8-valent, up to 16-valent urea compounds from thelysine-diamine intermediate 4 upon repeated conjugation of 4 withFmoc-Lys(Fmoc-OH) to produce a lysine-based multimeric urea dendron.

In accordance with an embodiment, the present invention provides Inaccordance with an embodiment, the present invention provides a compoundof formula I:

wherein Z is H, CO₂H, NH₂, SH and OH;wherein m is 2 to 16;wherein R₁ is the same or different moiety and is a compound of formulaVI:

wherein W is C₁ to C₁₀ alkyl, alkylamino, alkyl, alkylamino, alkenyl,alkynyl, hydroxyalkyl, alkoxy, dialkylamino thioalkyl, thioalkenyl,thioalkynyl, aryloxy, acyloxy, thioacyl, amido, and sulphonamido;wherein each of alkyl, or aryl moiety may be unsubstituted orsubstituted with one or more substituents selected from the groupconsisting of halo, hydroxy, carboxy, phosphoryl, phosphonyl, phosphonoC₁-C₆ alkyl, carboxy C₁-C₆ alkyl, dicarboxy C₁-C₆ alkyl, dicarboxy haloC₁-C₆ alkyl, sulfonyl, cyano, nitro, alkoxy, alkylthio, acyl, acyloxy,thioacyl, acylthio, aryloxy, amino, alkylamino, dialkylamino,trialkylamino, arylalkylamino, guanidino, aldehydo, ureido, andaminocarbonyl; W may be substituted with a chelating moiety, afluorescent dye or H, wherein when W is a chelating moiety, it can bebound to a metal ion useful in imaging, or as a cytotoxic moiety; and Lis a linker, wherein the linker is a C₈ to C₂₀ alkyl, alkylamino,alkenyl, alkynyl, hydroxyalkyl, alkoxy, dialkylamino thioalkyl,thioalkenyl, thioalkynyl, aryloxy, acyloxy, thioacyl, amido,polyethylene glycol and sulphonamido, wherein each of alkyl or arylmoiety may be unsubstituted or substituted with one or more substituentsselected from the group consisting of halo, hydroxy, carboxy,phosphoryl, phosphonyl, phosphono C₁-C₆ alkyl, carboxy C₁-C₆ alkyl,dicarboxy C₁-C₆ alkyl, dicarboxy halo C₁-C₆ alkyl, sulfonyl, cyano,nitro, alkoxy, alkylthio, acyl, acyloxy, thioacyl, acylthio, aryloxy,amino, alkylamino, dialkylamino, trialkylamino, arylalkylamino,guanidino, aldehydo, ureido, and aminocarbonyl; and alternatively, R₁ isa peptide ligand to an enzyme or endothelial receptor, and wherein R₂ isa chelating moiety, a fluorescent dye or H, wherein when R₂ is achelating moiety, it can be bound to a metal ion useful in imaging, oras a cytotoxic moiety; or a pharmaceutically acceptable salt, solvate,or stereoisomer thereof.

In one or more embodiments, L is a linker selected from the groupconsisting of:

As used herein, examples of the term “alkyl” preferably include a C₁₋₆alkyl (e.g., methyl, ethyl, propyl, isopropyl, butyl, isobutyl,sec-butyl, tert-butyl, pentyl, hexyl, etc.) and the like.

As used herein, examples of the term “alkenyl” preferably include C₂₋₆alkenyl (e.g., vinyl, allyl, isopropenyl, 1-butenyl, 2-butenyl,3-butenyl, 2-methyl-2-propenyl, 1-methyl-2-propenyl,2-methyl-1-propenyl, etc.) and the like.

As used herein, examples of the term “alkynyl” preferably include C₂₋₆alkynyl (e.g., ethynyl, propargyl, 1-butynyl, 2-butynyl, 3-butynyl,1-hexynyl, etc.) and the like.

Examples of the term “cycloalkyl” preferably include a C₃₋₈ cycloalkyl(e.g., a cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc.) and thelike.

Examples of the term “aryl” preferably include a C₆₋₁₄ aryl (e.g., aphenyl, 1-naphthyl, a 2-naphthyl, 2-biphenylyl group, 3-biphenylyl,4-biphenylyl, 2-anthracenyl, etc.) and the like.

Examples of the term “arylalkyl” preferably include a C₆₋₁₄ arylalkyl(e.g., benzyl, phenylethyl, diphenylmethyl, 1-naphthylmethyl,2-naphthylmethyl, 2,2-diphenylethyl, 3-phenylpropyl, 4-phenylbutyl,5-phenylpentyl, etc.) and the like.

The term “hydroxyalkyl” embraces linear or branched alkyl groups havingone to about ten carbon atoms any one of which may be substituted withone or more hydroxyl groups.

The term “alkylamino” includes monoalkylamino. The term “monoalkylamino”means an amino, which is substituted with an alkyl as defined herein.Examples of monoalkylamino substituents include, but are not limited to,methylamino, ethylamino, isopropylamino, t-butylamino, and the like. Theterm “dialkylamino” means an amino, which is substituted with two alkylsas defined herein, which alkyls can be the same or different. Examplesof dialkylamino substituents include dimethylamino, diethylamino,ethylisopropylamino, diisopropylamino, dibutylamino, and the like.

The terms “alkylthio,” “alkenylthio” and “alkynylthio” mean a groupconsisting of a sulphur atom bonded to an alkyl-, alkenyl- oralkynyl-group, which is bonded via the sulphur atom to the entity towhich the group is bonded.

Accordingly, included within the compounds of the present invention arethe tautomeric forms of the disclosed compounds, isomeric formsincluding enantiomers, stereoisomers, and diastereoisomers, and thepharmaceutically-acceptable salts thereof. The term “pharmaceuticallyacceptable salts” embraces salts commonly used to form alkali metalsalts and to form addition salts of free acids or free bases. Examplesof acids which may be employed to form pharmaceutically acceptable acidaddition salts include such inorganic acids as hydrochloric acid,sulphuric acid and phosphoric acid, and such organic acids as maleicacid, succinic acid and citric acid. Other pharmaceutically acceptablesalts include salts with alkali metals or alkaline earth metals, such assodium, potassium, calcium and magnesium, or with organic bases, such asdicyclohexylamine. Suitable pharmaceutically acceptable salts of thecompounds of the present invention include, for example, acid additionsalts which may, for example, be formed by mixing a solution of thecompound according to the invention with a solution of apharmaceutically acceptable acid, such as hydrochloric acid, sulphuricacid, methanesulphonic acid, fumaric acid, maleic acid, succinic acid,acetic acid, benzoic acid, oxalic acid, citric acid, tartaric acid,carbonic acid or phosphoric acid. All of these salts may be prepared byconventional means by reacting, for example, the appropriate acid orbase with the corresponding compounds of the present invention.

Salts formed from free carboxyl groups can also be derived frominorganic bases such as, for example, sodium, potassium, ammonium,calcium, or ferric hydroxides, and such organic bases as isopropylamine,trimethylamine, 2-ethylamino ethanol, histidine, procaine, and the like.

For use in medicines, the salts of the compounds of the presentinvention should be pharmaceutically acceptable salts. Other salts may,however, be useful in the preparation of the compounds according to theinvention or of their pharmaceutically acceptable salts.

In addition, embodiments of the invention include hydrates of thecompounds of the present invention. The term “hydrate” includes but isnot limited to hemihydrate, monohydrate, dihydrate, trihydrate and thelike. Hydrates of the compounds of the present invention may be preparedby contacting the compounds with water under suitable conditions toproduce the hydrate of choice.

As defined herein, in one or more embodiments, “contacting” means thatthe one or more compounds of the present invention are introduced into asample having at least one cancer cell expressing PSMA, and appropriateenzymes or reagents, in a test tube, flask, tissue culture, chip, array,plate, microplate, capillary, or the like, and incubated at atemperature and time sufficient to permit binding of the at least onecompound to the PSMA of the cancer cell. Methods for contacting thesamples with the compounds, and other specific binding components areknown to those skilled in the art, and may be selected depending on thetype of assay protocol to be run. Incubation methods are also standardand are known to those skilled in the art.

In another embodiment, the term “contacting” means that the at least onecompound of the present invention is introduced into a subject,preferably a subject receiving treatment for a PSMA related disorder,such as prostate cancer, and the at least one compounds is allowed tocome in contact with the PSMA in vivo.

Embodiments of the invention also include a process for preparingpharmaceutical products comprising the compounds. The term“pharmaceutical product” means a composition suitable for pharmaceuticaluse (pharmaceutical composition), as defined herein. Pharmaceuticalcompositions formulated for particular applications comprising thecompounds of the present invention are also part of this invention, andare to be considered an embodiment thereof.

As used herein, the term “treat,” as well as words stemming therefrom,includes preventative as well as disorder remitative treatment. Theterms “reduce,” “suppress,” “prevent,” and “inhibit,” as well as wordsstemming therefrom, have their commonly understood meaning of lesseningor decreasing. These words do not necessarily imply 100% or completetreatment, reduction, suppression, or inhibition.

With respect to pharmaceutical compositions described herein, thepharmaceutically acceptable carrier can be any of those conventionallyused, and is limited only by physico-chemical considerations, such assolubility and lack of reactivity with the active compound(s), and bythe route of administration. The pharmaceutically acceptable carriersdescribed herein, for example, vehicles, adjuvants, excipients, anddiluents, are well-known to those skilled in the art and are readilyavailable to the public. Examples of the pharmaceutically acceptablecarriers include soluble carriers such as known buffers which can bephysiologically acceptable (e.g., phosphate buffer) as well as solidcompositions such as solid-state carriers or latex beads. It ispreferred that the pharmaceutically acceptable carrier be one which ischemically inert to the active agent(s), and one which has little or nodetrimental side effects or toxicity under the conditions of use.

The carriers or diluents used herein may be solid carriers or diluentsfor solid formulations, liquid carriers or diluents for liquidformulations, or mixtures thereof.

Solid carriers or diluents include, but are not limited to, gums,starches (e.g., corn starch, pregelatinized starch), sugars (e.g.,lactose, mannitol, sucrose, dextrose), cellulosic materials (e.g.,microcrystalline cellulose), acrylates (e.g., polymethylacrylate),calcium carbonate, magnesium oxide, talc, or mixtures thereof.

For liquid formulations, pharmaceutically acceptable carriers may be,for example, aqueous or non-aqueous solutions, suspensions, emulsions oroils. Examples of non-aqueous solvents are propylene glycol,polyethylene glycol, and injectable organic esters such as ethyl oleate.Aqueous carriers include, for example, water, alcoholic/aqueoussolutions, cyclodextrins, emulsions or suspensions, including saline andbuffered media.

Examples of oils are those of petroleum, animal, vegetable, or syntheticorigin, for example, peanut oil, soybean oil, mineral oil, olive oil,sunflower oil, fish-liver oil, sesame oil, cottonseed oil, corn oil,olive, petrolatum, and mineral. Suitable fatty acids for use inparenteral formulations include, for example, oleic acid, stearic acid,and isostearic acid. Ethyl oleate and isopropyl myristate are examplesof suitable fatty acid esters.

Parenteral vehicles (for subcutaneous, intravenous, intraarterial, orintramuscular injection) include, for example, sodium chloride solution,Ringer's dextrose, dextrose and sodium chloride, lactated Ringer's andfixed oils. Formulations suitable for parenteral administration include,for example, aqueous and non-aqueous, isotonic sterile injectionsolutions, which can contain anti-oxidants, buffers, bacteriostats, andsolutes that render the formulation isotonic with the blood of theintended recipient, and aqueous and non-aqueous sterile suspensions thatcan include suspending agents, solubilizers, thickening agents,stabilizers, and preservatives.

Intravenous vehicles include, for example, fluid and nutrientreplenishers, electrolyte replenishers such as those based on Ringer'sdextrose, and the like. Examples are sterile liquids such as water andoils, with or without the addition of a surfactant and otherpharmaceutically acceptable adjuvants. In general, water, saline,aqueous dextrose and related sugar solutions, and glycols such aspropylene glycols or polyethylene glycol are preferred liquid carriers,particularly for injectable solutions.

In addition, in an embodiment, the compounds of the present inventionmay further comprise, for example, binders (e.g., acacia, cornstarch,gelatin, carbomer, ethyl cellulose, guar gum, hydroxypropyl cellulose,hydroxypropyl methyl cellulose, povidone), disintegrating agents (e.g.,cornstarch, potato starch, alginic acid, silicon dioxide, croscarmelosesodium, crospovidone, guar gum, sodium starch glycolate), buffers (e.g.,Tris-HCl, acetate, phosphate) of various pH and ionic strength,additives such as albumin or gelatin to prevent absorption to surfaces,detergents (e.g., Tween 20, Tween 80, Pluronic F68, bile acid salts),protease inhibitors, surfactants (e.g. sodium lauryl sulfate),permeation enhancers, solubilizing agents (e.g., cremophor, glycerol,polyethylene glycerol, benzalkonium chloride, benzyl benzoate,cyclodextrins, sorbitan esters, stearic acids), anti-oxidants (e.g.,ascorbic acid, sodium metabisulfite, butylated hydroxyanisole),stabilizers (e.g., hydroxypropyl cellulose, hydroxypropylmethylcellulose), viscosity increasing agents (e.g., carbomer, colloidalsilicon dioxide, ethyl cellulose, guar gum), sweeteners (e.g.,aspartame, citric acid), preservatives (e.g., thimerosal, benzylalcohol, parabens), lubricants (e.g., stearic acid, magnesium sterate,polyethylene glycol, sodium lauryl sulfate), flow-aids (e.g., colloidalsilicon dioxide), plasticizers (e.g., diethyl phthalate, triethylcitrate), emulsifiers (e.g., carbomer, hydroxypropyl cellulose, sodiumlauryl sulfate), polymer coatings (e.g., poloxamers or poloxamines),coating and film forming agents (e.g., ethyl cellulose, acrylates,polymethacrylates), and/or adjuvants.

The choice of carrier will be determined, in part, by the particularcompound, as well as by the particular method used to administer thecompound. Accordingly, there are a variety of suitable formulations ofthe pharmaceutical composition of the invention. The followingformulations for parenteral, subcutaneous, intravenous, intramuscular,intraarterial, intrathecal and interperitoneal administration areexemplary, and are in no way limiting. More than one route can be usedto administer the compounds, and in certain instances, a particularroute can provide a more immediate and more effective response thananother route.

Suitable soaps for use in parenteral formulations include, for example,fatty alkali metal, ammonium, and triethanolamine salts, and suitabledetergents include, for example, (a) cationic detergents such as, forexample, dimethyl dialkyl ammonium halides, and alkyl pyridiniumhalides, (b) anionic detergents such as, for example, alkyl, aryl, andolefin sulfonates, alkyl, olefin, ether, and monoglyceride sulfates, andsulfosuccinates, (c) nonionic detergents such as, for example, fattyamine oxides, fatty acid alkanolamides, and polyoxyethylenepolypropylenecopolymers, (d) amphoteric detergents such as, for example,alkyl-β-aminopropionates, and 2-alkyl-imidazoline quaternary ammoniumsalts, and (e) mixtures thereof.

The parenteral formulations will typically contain from about 0.5% toabout 25% by weight of the compounds in solution. Preservatives andbuffers may be used. In order to minimize or eliminate irritation at thesite of injection, such compositions may contain one or more nonionicsurfactants, for example, having a hydrophile-lipophile balance (HLB) offrom about 12 to about 17. The quantity of surfactant in suchformulations will typically range from about 5% to about 15% by weight.Suitable surfactants include, for example, polyethylene glycol sorbitanfatty acid esters, such as sorbitan monooleate and the high molecularweight adducts of ethylene oxide with a hydrophobic base, formed by thecondensation of propylene oxide with propylene glycol.

The parenteral formulations can be presented in unit-dose or multi-dosesealed containers, such as ampoules and vials, and can be stored in afreeze-dried (lyophilized) condition requiring only the addition of thesterile liquid excipient, for example, water, for injections,immediately prior to use. Extemporaneous injection solutions andsuspensions can be prepared from sterile powders, granules, and tablets.

Injectable formulations are in accordance with the invention. Therequirements for effective pharmaceutical carriers for injectablecompositions are well-known to those of ordinary skill in the art (see,e.g., Pharmaceutics and Pharmacy Practice, J. B. Lippincott Company,Philadelphia, Pa., Banker and Chalmers, eds., pages 238-250 (1982), andASHP Handbook on Injectable Drugs, Trissel, 15th ed., pages 622-630(2009)).

For purposes of the invention, the amount or dose of the compounds,salts, solvates, or stereoisomers of any one the compounds of Formula I,as set forth above, administered should be sufficient to effect, e.g., atherapeutic or prophylactic response, in the subject over a reasonabletime frame. The dose will be determined by the efficacy of theparticular compound and the condition of a human, as well as the bodyweight of a human to be treated.

The dose of the compounds, salts, solvates, or stereoisomers of any onethe compounds of Formula I, as set forth above, of the present inventionalso will be determined by the existence, nature and extent of anyadverse side effects that might accompany the administration of aparticular compound. Typically, an attending physician will decide thedosage of the compound with which to treat each individual patient,taking into consideration a variety of factors, such as age, bodyweight, general health, diet, sex, compound to be administered, route ofadministration, and the severity of the condition being treated. By wayof example, and not intending to limit the invention, the dose of thecompound can be about 0.001 to about 1000 mg/kg body weight of thesubject being treated/day, from about 0.01 to about 100 mg/kg bodyweight/day, about 0.1 mg to about 10 mg/kg body weight/day.

Radionuclides are generally classified as either being diagnostic ortherapeutic in their application. Although diagnostic imaging agentshave historically been a mainstay in the nuclear pharmacy industry,during the past decade there has been increased interest in thedevelopment and use of therapeutic radiotherapeutic imaging agents. Thisshift in focus has been elicited primarily from research involvingcombining radioactive radionuclides with sophisticated molecularcarriers. Because of radiation's damaging effect on tissues, it isimportant to target the biodistribution of radiopharmaceuticals asaccurately as possible. Generally speaking, PET uses imaging agentslabeled with the positron-emitters such as ¹⁸F, ¹³N and ¹⁵O, ⁷⁵Br, ⁷⁶Brand ¹²⁴I, SPECT uses imaging agents labeled with thesingle-photon-emitters such as ²⁰¹Tl, ^(99m)Tc, ¹²³I, ¹¹¹In and ¹³¹I.

Alpha-particle emitter radiopharmaceutical therapy (RPT) usesalpha-emitting radionuclides to kill the targeted cell or population ofcells. Examples of such alpha emitters include, for example, ²¹³Bilabeled agents and ²²⁵Ac labeled agents, for example.

As used herein, the term “antigen” is defined as any polypeptide orfragment thereof which selectively binds to a particular cell type in ahost through recognition of a cell-type specific (e.g. tumor cell orother host cell or population of cells) marker (e.g., antigen orreceptor. In other embodiments, the term “antigen” can mean a proteinreceptor on a cell membrane. PSMA is an example of such a proteinreceptor antigen. The cell targeting moiety can be an antibody orpeptide. Other proteins, enzymes and growth factors can also betargeting moieties. Targeting moieties can also be defined as anantibody or fragment thereof which selectively binds to a particularcell type in a host through recognition of a cell surface antigen.Preferred cell targeting antibodies are specific for solid tumors andcancer cells. Most preferred is PSMA for use in prostate cancers.

In an embodiment, the term “administering” means that the compounds ofthe present invention are introduced into a subject, preferably asubject receiving treatment for a disease, and the compounds are allowedto come in contact with the one or more disease related cells orpopulation of cells in vivo. In some embodiments the host cell orpopulation of cells in the host can be any cell or population of cellsthat can be selectively bound by the antigens bound to the compounds offormula I described above. One of ordinary skill in the art wouldunderstand the host cells can be cancer cells. In other embodiments, thehost cell or population of cells could be immunological cells, such as Bcells and T cells, or for example, other cells for which imaging orcytotoxic therapy is appropriate.

As used herein, the term “detection” “imaging” or “radiodetection” meansthe use of certain properties of isotopes and the energetic particlesemitted from radioactive material to obtain pharmacokinetic information.In addition, the term “scintigraphy” means a diagnostic test in which atwo-dimensional image of a body having a radiation source is obtainedthrough the use of radioisotopes. A radioactive chemical is injectedinto the patient which then concentrates in the target cells or organ ofinterest. By placing a camera that senses radioactivity over the body,an image of the target cells or organ of interest can be created. Theparticles can be detected by suitable devices such as gamma cameras,positron emission tomography (PET) machines, single photon emissioncomputed tomography (SPECT) machines and the like.

In some embodiments, the chelated metal is Tc, In, Ga. Y, Lu, Re, Cu,Ac, Bi, P Sm, Sc, Co, Ho, Gd, Eu, Tb, or Dy. In some embodiments themetal is an isotope, for example a radioactive isotope. In someembodiments, the isotope is Tc-94m, Tc-99m, In-111, G-67, Ga-68, Y-86,Y-90, Lu-177, Re-186, Re-188, Cu-64, Cu-67, Co-55, Co-57, Sc-47, Ac-225,Bi-213, Bi-212, Pb-212, Sm-153, Ho-166, or Dy-166.

In some embodiments, R₂ is a fluorescent dye moiety (FG) that emitslight in the visible or near infrared spectrum. FG includes anyadditional atoms or linkers necessary to attach the fluorescent dyemoiety to the rest of the compound. For instance linking groups havingalkyl, aryl, combination of alkyl and aryl, or alkyl and aryl groupshaving heteroatoms may be present in the chelating moiety, so long asthe linker does not interfere with the fluorescence of the dye.

In some embodiments, the fluorescent dye moiety includes apoly(ethyleneglycol) linker. Numerous fluorescent dye moieties are knownin the art, and will be readily apparent to one of ordinary skill. Manyfluorescent dyes are commercially available with activated groups usedto react with protein side chains or other compounds.

Examples of fluorescent compounds which may form all or part of thestructure of FG of the present invention include carbocyanine,indocarbocyanine, oxacarbocyanine, thiacarbocyanine, merocyanine,polymethine, coumarine, rhodamine, xanthene, fluorescein, andboron-dipyrromethane (BODIPY) compounds, to name a few.

Examples of fluorescent dye moieties include those described in WO20089/109832, which is incorporated by reference herein in its entirety.

Specific dyes that can be used with the compounds of the presentinvention, which emit in the near infrared spectrum include commerciallyavailable compounds Cy5, Cy5.5, and Cy7, available from GE Healthcare:VivoTag-680, VivoTag-5680, and VivoTag-5750, available from VisEnMedical: AlexaFiuor660, AlexaFiuor680, AlexaFiuor700, AlexaFiuor750, andAlexaFiuor790, available from Invitrogen; Dy677, Dy676, Dy682, Dy752,and Dy780, available from Dyonics; DyLight547, and Dylight647, availablefrom Pierce; Hilyte Fluor 647, Hilyte Fluor 680, and Hilyte Fluor 750,available from AnaSpec; IRDye 800CW, IRDye BOORS, and IRDye 700DX,available from Li-Cor; and ADS780WS, ADS830WS, and ADS832WS, availablefrom American Dye Source.

In accordance with another embodiment, the present invention provides acompound of formula II:

wherein Z is H, CO₂H, NH₂, SH and OH;wherein R₁ is the same or different moiety and is selected from thegroup consisting of:

and alternatively, R₁ is a peptide ligand to an enzyme or endothelialreceptor; and wherein R₂ is a chelating moiety, a fluorescent dye or H,wherein when R₂ is a chelating moiety, it can be bound to a metal ionuseful in imaging, or as a cytotoxic moiety; or a pharmaceuticallyacceptable salt, solvate, or stereoisomer thereof.

As used herein, the term “peptide ligand” is meant to mean an antigenbinding moiety which is specific for a known antigen, polypeptide orprotein receptor, and can be used interchangeably.

It will be understood by those of ordinary skill in the art that thecompounds of the present invention can be homomultivalent, meaning thatthe antigen binding moieties bound to the molecular scaffold are all thesame, for example, targeting PSMA. However, it is contemplated in thepresent invention, that the compounds can also be heteromultivalent.That is, that the antigen binding moieties bound to the molecularscaffold are not all the same. For example, a compound of the presentinvention can comprise antigen binding moieties to two or more differingantigens, such as, for example, PSMA and RGD.

In accordance with one or more embodiments of the present invention, theantigen binding moieties used in the compounds of the present inventioncan include, for example, hepsin, HER-2, ACPP, ADAM10, ADAM15, FN1,FOLH1, GNAl2, HRAS, KLK3, MMP3, MMP13, OCLN, SILV, integrins, VEGF,including VEGF1 and VEGF4, Robo-4, MMP2, MMP9, PDGF, TGF-α, and others.

In a further embodiment, the present invention provides a pharmaceuticalcomposition comprising a compound, salt, solvate, or stereoisomer of anyone of the compounds as set forth above, and a pharmaceuticallyacceptable carrier.

In another embodiment, the present invention provides a pharmaceuticalcomposition comprising a compound, salt, solvate, or stereoisomer of anyone of the compounds as set forth above, and at least on otherbiologically active agent and a pharmaceutically acceptable carrier.

In another embodiment, the present invention provides a pharmaceuticalcomposition comprising a compound, salt, solvate, or stereoisomer of anyone of the compounds as set forth above, and at least one or more otheranticancer compounds, and a pharmaceutically acceptable carrier.

In an embodiment, the present invention provides that the otheranticancer compounds can be, for example, anticancer drugs from thefollowing drug classes, including, but not limited to, antimitotics,antineoplastics, antimetabolites, and alkylating agents. Such classes ofanticancer drugs are well known in the art.

In an embodiment, the present invention provides methods of imaging PSMAon cells or a population of cells in a subject comprising administeringto the subject a compound, salt, solvate, or stereoisomer of any one ofthe compounds as set forth above, and at least on other biologicallyactive agent and a pharmaceutically acceptable carrier.

In accordance with an embodiment, the present invention provides the useof a compound, salt, solvate, or stereoisomer of any one of thecompounds as set forth above, and a pharmaceutically acceptable carrier,in the preparation of a medicament.

In accordance with another embodiment, the present invention providesthe use of a compound, salt, solvate, or stereoisomer of any one of thecompounds as set forth above, and at least on other biologically activeagent and a pharmaceutically acceptable carrier, in the preparation of amedicament.

In accordance with a further embodiment, the present invention providesthe use of a compound, salt, solvate, or stereoisomer of any one of thecompounds as set forth above, and at least one or more other anticancercompounds, and a pharmaceutically acceptable carrier, in the preparationof a medicament.

EXAMPLES

Solvents and chemicals obtained from commercial sources were ofanalytical grade or better and used without further purification. All9-fluorenylmethyloxycarbonyl (Fmoc) protected amino acids including theFmoc-Lys(Boc)-Wang resin andbenzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate(PyBOP) were purchased from Chem Impex International, Inc. (Wooddale,Ill.). Boc-Lys(Azide)-OH was purchased from Anaspec. Carrier-free[¹¹¹In]InCl₃ was purchased from MDS Nordion (Ottawa, ON, Canada).DOTANHS-ester (1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acidmono N-hydroxysuccinimide ester) was purchased from Macrocyclics, Inc.(Dallas, Tex.).

Indium (III) nitrate, 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline(EEDQ), triethylsilane (Et3SiH), N,Ndiisopropylethylamine (DIEA) andtriethylamine (TEA) were purchased from Sigma-Aldrich (Saint Louis,Mo.). All other chemicals were purchased from Thermo Fisher Scientific(Pittsburgh, Pa.) unless otherwise specified. Analytical thin-layerchromatography (TLC) was performed using Aldrich aluminum-backed 0.2 mmsilica gel Z19, 329-1 plates and visualized by ultraviolet light (254nm), I₂ and 1% ninhydrin in EtOH. Flash chromatography was performedusing MP SiliTech 32-63 D 60 Å silica gel purchased from Bodman (Aston,Pa.). All experiments were performed in duplicate or triplicate toensure reproducibility. ¹H NMR spectra were recorded on a BrukerUltrashield™ 400 MHz spectrometer. Chemical shifts (6) are reported inppm downfield by reference to proton resonances resulting fromincomplete deuteration of the NMR solvent. Low resolution ESI massspectrawere obtained on a Bruker Daltonics Esquire 3000 Plusspectrometer. High resolution mass spectra were obtained by theUniversity of Notre Dame Mass Spectrometry & Proteomics Facility, NotreDame, Ind. using ESI by direct infusion on a Bruker micrOTOF-II.

High-performance liquid chromatographic purification of compounds 1-3were performed using a Phenomenex C₁₈ Luna 10×250 mm₂ column on a Waters600E Delta LC system with a Waters 486 variable wavelength UV/Visdetector, both controlled by Empower software. For HPLC purification ofradiolabeled [¹¹¹In]₃, a Waters Novapak C₁₈150×3.9 mm₂ column was used.HPLC was performed using the following methods. Method 1: Solvent A(0.1% TFA in water) and solvent B (0.1% TFA in CH₃CN), flow rate 8mL/min. The elution gradient was 95% A and 5% B for 5 min and 95% A to50% A and 5% B to 50% B over 5-35 min; Method 2: The elution gradientwas 95% A and 5% B for 5 min and 95% A to 70% A and 5% B to 30% B over5-35 min, Method 3: Solvent A (0.1% TFA in water) and solvent B (0.1%TFA in methanol), flow rate 8 mL/min. The elution gradient was 0-5 min,77% A and 23% B for 0-5 min, 77% A to 70% A and 23% B to 30% B for 5-35min, and 70% A to 77% A and 30% B to 23% B for 35 min. Method 4: SolventA (0.1% TFA in water) and solvent B (0.1% TFA in CH₃CN), flow rate 1mL/min. The elution gradient was 83% A and 17% B for 0-5 min, and 83% Ato 70% A and 17% B to 30% B for 5-25 min.

PSMA Inhibition. The PSMA inhibitory activities of 1-3 and[^(113/115)In]3 were determined using a fluorescence-based assayaccording to a previously reported procedure (J Med Chem. 2008;51:7933-7943). Briefly, lysates of LNCaP cell extracts (25 μL) wereincubated with the inhibitor (12.5 μL) in the presence of 4 μM NAAG(12.5 μL) for 120 min. The amount of glutamate released upon hydrolysisof NAAG was measured by incubating with a working solution (50 μL) ofthe Amplex Red Glutamic Acid Kit (Life Technologies, Grand Island, N.Y.)for 60 min. Fluorescence was measured with a VICTOR3V multilabel platereader (Perkin Elmer Inc., Waltham, Mass.) with excitation at 530 nm andemission at 560 nm. Inhibition curves were determined using semi-logplots and IC₅₀ values were determined at the concentration at whichenzyme activity was inhibited by 50%. Assays were performed intriplicate. Enzyme inhibitory constants (Ki values) were generated usingthe Cheng-Prusoff conversion. Data analysis was performed using GraphPadPrism version 4.00 for Windows (GraphPad Software, San Diego, Calif.).

Cell Culture and Animal Models. Sublines of the androgen independentPC-3 human prostate cancer xenograft originally derived from an advancedandrogen independent bone metastasis were used. Those sublines have beenmodified to express high (PC-3 PIP) and low (PC-3 flu) PSMA levels andwere generously provided by Dr. Warren Heston (Cleveland Clinic). BothPSMA-expressing (PC-3 PIP) and nonexpressing (PC-3 flu) prostate cancercell lines were grown in RPMI 1640 medium (Mediatech Inc., Manassas,Va.) containing 10% fetal bovine serum (FBS) (Sigma Aldrich, St. Louis,Mo.) and 1% Pen-Strep (Mediatech Inc., Manassas, Va.) as previouslydescribed (Clin. Cancer Res. 2008; 14:3036-3043). All cell cultures weremaintained at 5% carbon dioxide (CO₂), at 37° C. in a humidifiedincubator. Animal studies were carried out in full compliance with theregulations of the Johns Hopkins Animal Care and Use Committee. Six- toeight-week-old male, non-obese diabetic (NOD)/severe-combinedimmunodeficient (SCID) mice (Johns Hopkins Animal Core, Baltimore, Md.)were implanted subcutaneously (s.c.) with PC-3 PIP (PSMA+) and PC-3 flu(PSMA−) cells (2×10⁶ in 100 μL of Matrigel) at the forward right andleft flanks, respectively. Mice were imaged or used in biodistributionassays when the xenografts reached 5 to 7 mm in diameter.

Gamma Scintigraphy and SPECT/CT. Compound [¹¹¹In]3 was imaged using maleSCID mice. Xenograft models were generated as described above. Mice wereanesthetized using 1% isoflurane in oxygen flowing at 0.6 L/min prior toand during radiochemical injection. Mice were injected via the tail veinwith approximately 1.2 mCi (44.4 MBq) of [¹¹¹In]3 formulated in 100 μLof saline, pH 7. After allowing for 30-60 min of radiochemical uptake,anesthetized mice were placed on the scanner gantry and secured withmedical tape while the anesthetic flow was increased to 0.8 L/min. Thebody temperature of the mice was maintained by covering them withseveral layers of absorbent, disposable pads and illumination with adissection lamp during scanning. Single-pinhole median-energy (PHME)collimators with an aperture size of 1.0 mm, and stepwise rotation for64 projection angles in a full 360° rotation, 40 s increments were usedfor SPECT imaging. The radius of rotation (ROR) was set at 7 cm, whichprovided a field of view of 7.5 cm to cover the mouse body from head tobladder. A CT scan was performed prior to scintigraphy for bothanatomical co-registration and attenuation correction. A total of 512projections were acquired in a 2 min continuous rotation mode covering afull 360° rotation. Data were reconstructed and fused using commercialsoftware from the vendor (Gamma Medica-Ideas, Northridge, Calif.), whichincludes a 2D-OSEM algorithm. Data were analyzed and volume-renderedimages were generated using AMIDE software (SourceForge,amide.sourceforge.net/).

Biodistribution. PSMA+PC-3 PIP and PSMA-PC-3 flu xenografts bearing SCIDmice were injected via the tail vein with 0.74 MBq (20 μCi) of [¹¹¹In]3.Four mice were sacrificed by cervical dislocation at 2 and 24 h p.i. Theheart, lungs, liver, stomach, pancreas, spleen, fat, kidney, muscle,small and large intestines, urinary bladder, and PC-3 PIP and flu tumorswere quickly removed. A 0.1 mL sample of blood was also collected. Eachorgan was weighed, and the tissue radioactivity was measured with anautomated gamma counter (1282 Compugamma CS, Pharmacia/LKB Nuclear,Inc., Gaithersburg, Md.). The percentage injected dose per gram oftissue (% ID/g) was calculated by comparison with a standard dilution ofthe initial dose. All measurements were corrected for radioactive decay

Example 1

(3S,7S)-26-Azido-5,13,20-trioxo-4,6,12,21-tetraazahexacosane-1,3,7,22-tetracarboxylicacid, compound 1. This compound was prepared following our previousreport (J. Nucl. Med., (SNM Annual Meeting Abstract). 2011; 52(Supplement 1): 293). Briefly, commercially available Boc-Lys(Azide)-OHwas treated with a solution of TFA/CH₂Cl₂ (1:1) at ambient temperaturefor 4 h to remove the Boc group. After solvent removal, the crudeproduct, H-Lys(azide)-OH, was directly used for the next step. To asolution of H-Lys(azide)-OH (50 mg, 0.29 mmol in 500 μL DMSO) was addedNHS-ester of Lys-Glu urea (24 mg, 0.43 mmol in 500 μL DMSO) and DIEA(100 μL) and left at ambient temperature for 4 h. Solvent was evaporatedto dryness and the residue was dissolved in water and purified by HPLC(Method 1). Retention time (Rt): 17.1 min. 1H NMR (δ, ppm, DMSO): 8.06(m, 2H), 7.74 (m, 2H), 6.34-6.29 (m, 2H), 4.16-4.03 (m, 3H), 3.00 (m,2H), 2.33-1.27 (m, 28H). ESI-MS m/Z: 630 [M+H]+.

Example 2 6-amino-2-(2,6-dipropiolamidohexanamido)hexanoic acid,compound 4

Compound 4 was synthesized using standard Fmoc mediated solid phasepeptide synthesis. Formation and masking of free amines was assessedusing the Kaiser test. Washing the resin with 3 mL DMF three times, 1minute each, before and after each step was performed until liberationof the final product from the resin. All steps were performed at ambienttemperature unless otherwise mentioned. After being swollen by 3 mL DMF,Fmoc-Lys-(Boc)-Wang resin (500 mg, 0.18 mM) was deprotected by settlingwith 3 mL 20% piperidine in DMF×2, 5 min each time, before coupling withFmoc-Lys-(Fmoc)-OH (318 mg, 0.54 mM) preactivated with DIEA (124 μL,0.72 mM) and PyBOP (280 mg, 0.54 mM in 3 mL DMF). The last coupling wasperformed twice, 30 minutes in duration each time. The Fmoc groups wereremoved using 3 mL 20% piperidine in DMF×2, 5 min each time. Couplingwith propiolic acid (75 mg, 1.08 mM) was achieved using a solution ofEEDQ (268 mg, 1.08 mM) as a coupling reagent in 2 mL DMF and acceleratedvia exposure to microwave irradiation×5, 30 sec each time. Ten percentof the maximum power of a standard kitchen microwave was enough toachieve complete coupling as indicated by a negative Kaiser test.Cleavage of 4 from the resin was achieved by settling with 2 mLTFA/H₂O/TES (95/2.5/2.5) mixture for 30 min followed by washing twicewith 2 mL 100% TFA. The collected fractions were evaporated under vacuumafter which the concentrated product was purified using a Sep-Pak® Vac35 cc tC₁₈ tube (Waters, WAT043350). Compound 4 was eluted with 5%acetonitrile in water (0.1% TFA). HPLC: Method 2, R_(t): 10 min. ¹H NMR(DMSO-d₆) (δ, ppm): 8.89 (m, 1H) 8.72 (m, 1H), 8.21 (m, 2H), 7.73 (m,2H), 4.23 (m, 1H) 4.16-4.10 (m, 4H), 3.04 (m, 2H), 2.77 (m, 2H),1.74-1.27 (m, 12H). ESIMS m/Z: 379 [M+H]+.

Example 3 (7S)-26-(4-((1-((5-amino-1-carboxypenty1)amino)-1-oxo-6-(1-((7S)-1,3,7,22-tetracarboxy-5,13,20-trioxo-4,6,12,21-tetraazahexacosan-26-yl)1H-1,2,3-triazole-4-carboxamido)hexan-2-yl)carbamoyl)-1H-1,2,3-triazol-5-yl)-5,13,20-trioxo-4,6,12,21-tetraazahexacosane-1,3,7,22-tetracarboxylicacid, PSMA-targeted homobivalent compound 2

Compound 1 (49 mg, 76.7 μM) and 4 (0.5 eq, 14.5 mg, 38.3 μM) weredissolved in 1 mL H₂O/t-BuOH (1/1). To that solution, sodium ascorbate(6 mg, 30 μM) and Cu(OAc)₂ (3 mg, 15 μM) were added consecutively, themixture was purged with N₂ gas and stirred at ambient temperatureovernight. Compound 2 was purified using C₁₈ SepPak® Vac 2 g columnthrough which the product was successfully eluted using 70/30water/acetonitrile (0.1% TFA). Compound 2 was further purified by HPLC(Method 1). Rt: 13.9 min. ESI-MS m/Z: 1638 [M+H]+.

Example 4(7S)-26-(4-((1-((1-carboxy-5-(2-(4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-1-yl)acetamido)pentyl)amino)-1-oxo-6-(1-((7S)-1,3,7,22-tetracarboxy-5,13,20-trioxo-4,6,12,21-tetraazahexacosan-26-yl)-1H-1,2,3-triazole-4-carboxamido)hexan-2-yl)carbamoyl)-1H-1,2,3-triazol-5-yl)-5,13,20-trioxo-4,6,12,21-tetraazahexacosane-1,3,7,22-tetracarboxylicacid, DOTA conjugated PSMA-targeted homobivalent compound 3

To a solution of 2 (4 mg, 2.44 μM in 500 μL DMF) was added DOTA-NHSester (1.5 mg, 3.66 μM in 500 μL DML) and DIEA (50 μL) and left atambient temperature for 4 h. Solvent was removed under vacuum and theresidue was dissolved in 2 mL water and was purified using HPLC Method3. R_(t): 26.2 min ESIMS m/Z: 2024[M+H]+, HRESI-MS (m/z): HRESI-MS m/Z:Calcd. for C₈₅H₁₃₅N₂₂O₃₄, 2023.9824. Found 2023.9820.

Example 5 Compound [^(113/115)In]3

To a solution of In(NO₃)₃ (1 mg, 20 μmol in 100 μL) in deionized waterwas added 3 (1 mg, 0.48 μmol) in 500 μL 0.3 M NaOAc. The resultingsolution was heated at 95° C. for 1 h. The solution was purified by HPLCMethod 3. The retention time for the product was at 25.8 min. Yield:˜50%. ESIMS m/Z: 1067 [M+H]²⁺

Example 6 Compound [¹¹³In]3

For each radiolabeling reaction, approximately 50-70 μg of 3 in 300 mMNaOAc (purged under N₂ for 2-3 min) was incubated with 111-148 MBq (3-4mCi)¹¹¹InCl₃ at pH 5.5-6 for 20 h at 95° C. The reaction solution wasdiluted with 1 mL water. Complexation was monitored by injectingaliquots of 20-40 μL of the solution onto the HPLC. The radiolabeledproduct [¹¹¹In]3 was obtained in ˜70-90% radiochemical yield and theradiochemical purity was >98% as measured by ITLC (Gelman ITLC strips,10 mM EDTA). HPLC Method 4 was used to purify the radiolabeled product[¹¹¹In]3. Rt: 13.5 min for the desired product and R_(t): 15.4 min forthe free ligand. The specific radioactivity of the agent was ˜8.4-204.4GB/μmol. The acidic eluate was neutralized with 100 μL of PBS solutionand the volume of the eluate was reduced under vacuum to dryness. Thesolid residue was diluted with saline to the desired radioactivityconcentration for biodistribution and imaging studies.

Example 7

To evaluate the anticipated multivalent effect, a versatileLys-Glu-urea-based azide intermediate (1) was prepared to serve as amonovalent control compound (FIG. 1) against the bivalent compound 2 andthe DOTA-chelated bivalent urea analog, 3 to examine the effect ofadding a chelating agent to bivalent urea 2. Compounds 2 and 3 wereconveniently prepared by employing simple peptide coupling and clickchemistry (Angew Chem Int Ed. 1963; 2:565-598; Angewandte Chemie(International ed.) 2002; 41:2596-2599.) as shown in Scheme 1 (FIG. 2).

Starting with commercially available Fmoc-Lys(Boc)-Wang resin and usingstandard Fmoc-based solid phase peptide chemistry, 1-4 were prepared insuitable yields. In brief, Fmoc-Lys(Boc)-Wang was treated with 20%piperidine/DMF to remove the Fmoc group followed by coupling withcommercially available Fmoc-Lys(Fmoc)-OH in the presence ofbenzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate(PyBOP) and N,N-diisopropylethylamine (DIEA). In the next step, amicrowave-assisted coupling reaction was performed using propiolic acidin presence of 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (EEDQ) inDMF to improve the yield and purity of the desired product. Finally, 4was isolated in ˜40% yield after treating the resin with a cocktail ofTFA/H₂O/TES (95/2.5/2.5) at ambient temperature for 0.5 h. Compound 4, aLys-based (α-, ε-)dialkyne peptide, served as the key intermediate tointroduce multimerization. Copper catalyzed click chemistry was employedusing the azide intermediate 1 and dialkyne peptide 4 to producemultivalent compound 2 in moderate yield after purification byhigh-performance liquid chromatography (HPLC). Compound 3 was preparedby coupling the free amine of the lysine residue of 2 with theN-hydroxysuccinimide ester of DOTA tris-acid using DIEA as a base inDMSO at ambient temperature for 4 h. Compound 3 was purified by HPLC andobtained in ˜15% overall yield. Compound 3 was labeled with ¹¹¹In at 95°C. in 0.3 M NaOAc buffer within 20 min in ˜70-90% yield and specificradioactivity of ˜8.4-204.4 GB/μmol.

Example 8

PSMA inhibition constant (K_(i)) values for 1-3 were determined using afluorescence-based PSMA inhibition assay. The data are presented inTable 1. As revealed from the Ki values, the binding affinity was foundto increase 5-fold from monovalent 1 to bivalent 2. Interestingly, therewas an 11-fold increase to the DOTA-chelated bivalent compound 3compared to 1 leading to subnanomolar binding affinity for 3. Under thesame experimental conditions, the Ki value of the known PSMA inhibitorZJ-43 was 1.16 nM, indicating the high inhibitory potency of 3. Theinhibition curves of 1-3, which are expressed with respect to the amountof glutamate released from hydrolysis of the natural PSMA substrate,N-acetylaspartylglutamate (NAAG), are shown in FIG. 3. A structurallysimilar triazole version of 1, compound 6 (FIG. 1, Table 1) was alsotested for PSMA inhibitory activity in vitro. The Ki value of 6 was 0.92nM in that experiment, in which ZJ-43 demonstrated a Ki value of 0.35(95% CI, 0.2-0.6 nM), suggesting that the affinity of 6 is likelysignificantly less than the bivalent compounds 2 or 3. Compound 6 wasradiolabeled with 99mTc and its biological properties were tested invivo. A manuscript describing those biological data is in preparation.

TABLE 1 PSMA Inhibitory activity Compound Ki [nM] 95% CI of Ki 1 0.910.58 nM to 1.45 nM 2 0.10 0.07 nM to 0.16 nM 3 0.08 0.05 nM to 0.12 nMZJ43 1.16 0.92 nM to 1.46 nM 6 0.92* 0.06 nM to 12 nM *separateexperiment (see text)

Example 9

FIG. 2 shows the pharmacokinetic behavior of [¹¹¹In]3 in vivo in SCIDmice bearing both PSMA+PC3-PIP and PSMA-PC3-flu xenografts. It waspreferred to use the isogenic PSMA+PIP vs PSMA-flu comparison as the twocell lines are phenotypically identical, differing only in PSMAexpression. In this experiment 44.4 MBq (1.2 mCi) of [¹¹¹In]3 wasadministered intravenously and the animal was imaged repeatedly over aneight day period. Intense radiotracer uptake was seen only in thePSMA+PIP tumors and in the kidneys. Kidney uptake of the radiotracer ispartially due to its route of excretion as well as to specific uptakefrom the expression of PSMA in mouse kidneys. Clearance of radioactivityfrom kidney and non-target tissues was more rapid than from target tumorsuch that by 48 h post-injection (p.i.) a high tumor/background ratiowas observed (FIG. 4). Significantly, PSMA+ tumor was possible to imageout to eight days p.i. To validate the in vivo imaging data, [¹¹¹In]3was also assessed for its pharmacokinetics ex vivo. Table 2 shows thepercentage injected dose per gram (% ID/g) of radiotracer in selectedorgans at 2 h and 24 h p.i. Compound [¹¹¹In]3 displayed PSMA-dependentbinding in PSMA+PC3-PIP xenografts with continuous accumulation at thetumor site out to 24 h. We observed tumor uptake values of 31.93±5.87and 34.03±7.53% ID/g (SEM) at 2 and 24 h, respectively. The blood,spleen, gastrointestinal tract, kidney and bladder displayed the highestuptake at 2 h. Steady clearance from the kidneys was demonstrated, from168.67±14.12 at 2 h to 66.86±14.22% ID/g at 24 h. The tumor uptakevalues of [¹¹¹In]3 compare favorably with low molecular weightmonovalent PSMA imaging agents [10, 13, 14, 16, 22, 28-31], includingN—[N—[(S)-1,3-dicarboxypropyl]carbamoyl]-4-[¹⁸F]fluorobenzyl-L-cysteine,N—[N—[(S)-1,3-Dicarboxypropyl]carbamoyl]-4-[¹⁸F]fluorobenzyl-1-cysteine(DCFBC) (Cancer Biol Ther. 2008; 7:974-982), which has recently beenadministered to human subjects.

TABLE 2 Biodistribution of [¹¹¹In]3 2 hours 24 hours Blood 0.12 ± 0.040.02 ± 0.01 Heart 0.16 ± 0.05 0.03 ± 0.01 Lung 1.84 ± 0.26 0.17 ± 0.04Liver 0.19 ± 0.03 0.16 ± 0.03 Stomach 0.22 ± 0.07 0.03 ± 0.01 Pancreas0.43 ± 0.10 0.05 ± 0.02 Spleen 12.33 ± 3.02  0.64 ± 0.22 Fat 0.57 ± 0.170.19 ± 0.23 Kidney 168.67 ± 14.18  66.86 ± 14.22 Muscle 0.16 ± 0.08 0.03± 0.01 Small intestine 0.10 ± 0.03 0.04 ± 0.01 Large intestine 0.27 ±0.05 0.05 ± 0.03 Bladder 2.61 ± 1.36 0.52 ± 0.27 PC-3 PIP 31.93 ± 5.87 34.03 ± 7.53  PC-3 flu 0.16 ± 0.03 0.09 ± 0.03 PIP: flu 203   379 PIP:blood 257 2,254 PI: muscle 199 1,220 Results are expressed as thepercentage injected doseper gram (% ID/g) of tissue; n = 4

Example 10

The in vivo properties of the bivalent compound [¹¹¹In]3, were alsocompared with that of one of our lead DOTA-chelated monovalentcompounds, [¹¹¹In]5 (FIG. 5) and Table 3). PSMA+ tumor uptake for[¹¹¹In]5 at 2 h p.i. was 29.72±8.09% ID/g, in the same range as that forthe bivalent compound [¹¹¹In]3. However at 24 h p.i. monovalent [111In]5showed significantly lower uptake (23.17±3.53% ID/g) than bivalent[¹¹¹In]3 (34.03±7.53% ID/g). At all time points renal retention of[¹¹¹In]5 was significantly lower than that for [¹¹¹In]3. The prolongedtumor retention and rapid clearance from non-target tissues led to veryhigh target to non-target ratios for the bivalent [¹¹¹In]3 at 24h:PSMA+PIP to PSMA-flu tumor ratio of 379; tumor to blood ratio of2,254; and, tumor-to-muscle ratio of 1,220. The corresponding monovalentcompound [¹¹¹In]5 demonstrated values of 265, 1,027 and 1,136, in therespective comparisons. The higher uptake and significant retention of[¹¹¹In]3 compared to [¹¹¹In]5 in tumors reflects the advantages of themultimeric design of the former, which affords improved retention invivo in addition to the anticipated multivalent effects on targetbinding affinity. One explanation for those results could be that thebinding of one PSMA-targeting moiety would significantly enhance thelocal concentration of the other PSMA-targeting moiety of the homodimerin the vicinity of the active site of PSMA, which may lead to a fasterrate of receptor binding or a slower rate of dissociation and translateinto higher uptake and longer retention time in the tumor. The apparentincrease in molecular size may also prolong circulation time of thedimer and consequently reduce the tumor washout rate.

TABLE 3 Biodistribution of [¹¹¹In]5 2 hours 24 hours Blood 0.28 ± 0.050.02 ± 0.01 Heart 0.16 ± 0.04 0.03 ± 0.01 Lung 1.12 ± 0.32 0.10 ± 0.02Liver 0.25 ± 0.07 0.17 ± 0.02 Stomach 0.19 ± 0.05 0.04 ± 0.01 Pancreas0.24 ± 0.05 0.04 ± 0.01 Spleen 4.88 ± 2.63 0.32 ± 0.06 Fat 0.83 ± 0.610.02 ± 0.01 Kidney 110.31 ± 15.96  7.52 ± 2.38 Muscle 0.12 ± 0.04 0.02 ±0.01 Small intestine 0.17 ± 0.04 0.05 ± 0.01 Large intestine 0.21 ± 0.070.06 ± 0.02 Bladder 0.91 ± 0.37 0.37 ± 0.16 PC-3 PIP 29.72 ± 8.09  23.17± 3.53  PC-3 flu 0.22 ± 0.05 0.09 ± 0.02 PIP: flu 133  264 PIP: blood106 1027 PI: muscle 242 1136 Results are expressed as the percentageinjected doseper gram (% ID/g) of tissue; n = 4

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

1. A compound of formula I:

wherein Z is H, CO₂H, NH₂, SH and OH; wherein m is 2 to 16; wherein R₁is the same or different moiety and is a compound of formula VII:

wherein W is C₁ to C₁₀ alkyl, alkylamino, alkyl, alkylamino, alkenyl,alkynyl, hydroxyalkyl, alkoxy, dialkylamino thioalkyl, thioalkenyl,thioalkynyl, aryloxy, acyloxy, thioacyl, amido, and sulphonamido;wherein each of alkyl, or aryl moiety may be unsubstituted orsubstituted with one or more substituents selected from the groupconsisting of halo, hydroxy, carboxy, phosphoryl, phosphonyl, phosphonoC₁-C₆ alkyl, carboxy C₁-C₆ alkyl, dicarboxy C₁-C₆ alkyl, dicarboxy haloC₁-C₆ alkyl, sulfonyl, cyano, nitro, alkoxy, alkylthio, acyl, acyloxy,thioacyl, acylthio, aryloxy, amino, alkylamino, dialkylamino,trialkylamino, arylalkylamino, guanidino, aldehydo, ureido, andaminocarbonyl; W may be substituted with a chelating moiety, afluorescent dye or H, wherein when W is a chelating moiety, it can bebound to a metal ion useful in imaging, or as a cytotoxic moiety; and Lis a linker, wherein the linker is a C₈ to C₂₀ alkyl, alkylamino,alkenyl, alkynyl, hydroxyalkyl, alkoxy, dialkylamino thioalkyl,thioalkenyl, thioalkynyl, aryloxy, acyloxy, thioacyl, amido,polyethylene glycol and sulphonamido, wherein each of alkyl or arylmoiety may be unsubstituted or substituted with one or more substituentsselected from the group consisting of halo, hydroxy, carboxy,phosphoryl, phosphonyl, phosphono C₁-C₆ alkyl, carboxy C₁-C₆ alkyl,dicarboxy C₁-C₆ alkyl, dicarboxy halo C₁-C₆ alkyl, sulfonyl, cyano,nitro, alkoxy, alkylthio, acyl, acyloxy, thioacyl, acylthio, aryloxy,amino, alkylamino, dialkylamino, trialkylamino, arylalkylamino,guanidino, aldehydo, ureido, and aminocarbonyl; and alternatively, R₁ isa peptide ligand to an enzyme or endothelial receptor, and wherein R₂ isa chelating moiety, a fluorescent dye or H, wherein when R₂ is achelating moiety, it can be bound to a metal ion useful in imaging, oras a cytotoxic moiety; or a pharmaceutically acceptable salt, solvate,or stereoisomer thereof.
 2. The compound of formula I, wherein L is alinker selected from the group consisting of:


3. A compound of formula II:

wherein Z is H, CO₂H, NH₂, SH and OH; wherein R₁ is the same ordifferent moiety and is selected from the group consisting of:

and alternatively, R₁ is a peptide ligand to an enzyme or endothelialreceptor; and wherein R₂ is a chelating moiety, a fluorescent dye or H,wherein when R₂ is a chelating moiety, it can be bound to a metal ionuseful in imaging, or as a cytotoxic moiety; or a pharmaceuticallyacceptable salt, solvate, or stereoisomer thereof.
 4. A compound offormula VI:

wherein R₁ is the same or different moiety and is a compound of formulaVII:

wherein W is C₁ to C₁₀ alkyl, alkylamino, alkyl, alkylamino, alkenyl,alkynyl, hydroxyalkyl, alkoxy, dialkylamino thioalkyl, thioalkenyl,thioalkynyl, aryloxy, acyloxy, thioacyl, amido, and sulphonamido;wherein each of alkyl, or aryl moiety may be unsubstituted orsubstituted with one or more substituents selected from the groupconsisting of halo, hydroxy, carboxy, phosphoryl, phosphonyl, phosphonoC₁-C₆ alkyl, carboxy C₁-C₆ alkyl, dicarboxy C₁-C₆ alkyl, dicarboxy haloC₁-C₆ alkyl, sulfonyl, cyano, nitro, alkoxy, alkylthio, acyl, acyloxy,thioacyl, acylthio, aryloxy, amino, alkylamino, dialkylamino,trialkylamino, arylalkylamino, guanidino, aldehydo, ureido, andaminocarbonyl; W may be substituted with a chelating moiety, afluorescent dye or H, wherein when W is a chelating moiety, it can bebound to a metal ion useful in imaging, or as a cytotoxic moiety; and Lis a linker, wherein the linker is a C₈ to C₂₀ alkyl, alkylamino,alkenyl, alkynyl, hydroxyalkyl, alkoxy, dialkylamino thioalkyl,thioalkenyl, thioalkynyl, aryloxy, acyloxy, thioacyl, amido,polyethylene glycol and sulphonamido, wherein each of alkyl or arylmoiety may be unsubstituted or substituted with one or more substituentsselected from the group consisting of halo, hydroxy, carboxy,phosphoryl, phosphonyl, phosphono C₁-C₆ alkyl, carboxy C₁-C₆ alkyl,dicarboxy C₁-C₆ alkyl, dicarboxy halo C₁-C₆ alkyl, sulfonyl, cyano,nitro, alkoxy, alkylthio, acyl, acyloxy, thioacyl, acylthio, aryloxy,amino, alkylamino, dialkylamino, trialkylamino, arylalkylamino,guanidino, aldehydo, ureido, and aminocarbonyl; and alternatively, R₁ isa peptide ligand to an enzyme or endothelial receptor, and wherein R isa chelating moiety, a fluorescent dye or H, wherein when R is achelating moiety, it can be bound to a metal ion useful in imaging, oras a cytotoxic moiety; or a pharmaceutically acceptable salt, solvate,or stereoisomer thereof.
 5. The compound of formula V, wherein L is alinker selected from the group consisting of:


6. A compound of formula VI:

wherein R₁ is the same or different moiety and is selected from thegroup consisting of:

and alternatively, R₁ is a peptide ligand to an enzyme or endothelialreceptor; and wherein R is a chelating moiety, a fluorescent dye or H,wherein when R is a chelating moiety, it can be bound to a metal ionuseful in imaging, or as a cytotoxic moiety; or a pharmaceuticallyacceptable salt, solvate, or stereoisomer thereof.
 7. A pharmaceuticalcomposition comprising a compound, salt, solvate, or stereoisomer ofclaim 1, and a pharmaceutically acceptable carrier.
 8. A pharmaceuticalcomposition comprising a compound, salt, solvate, or stereoisomer ofclaim 1, and at least one or more other biologically active agents.
 9. Apharmaceutical composition comprising a compound, salt, solvate, orstereoisomer of claim 1, and at least one or more other anticancercompounds.
 10. A method of treating or preventing cancer in a subjectcomprising administering to the subject an effective amount of acompound, salt, solvate, or stereoisomer of claim
 1. 11. The method ofclaim 10, wherein the cancer is prostate cancer.
 12. A method of imagingprostate cancer in a subject comprising administering to the subject aneffective amount of a compound, salt, solvate, or stereoisomer of claim1, or pharmaceutical compositions thereof, wherein R or R₂ is an metalion or dye useful for imaging.